Cementitious article of manufacture



1'55; amiss; comma on msut.

Patented Jan. 5, 1943 J c ea, or China-wood oil,

'{caiimi iirrr'ous TAn'ric E' a N m T F- ;.l

7 John C. Maclldowie, Nashua, N. IL, assignor to Johns-Manville Corporation, New York, N. Y.,

1 acornoration of Newxork 1 f'- I mowing;- Kpiiucauon Aprili 3 1938,f

- s ia mzorcis cement therein, and then preventing further curing of the cement. The invention comprises,

Cross Reference (c1. 11'1 12 s) The proportions of the set eral ingredients are This invention relatesto a sis-e16 of naii'u weight or the fims e When l5 mentitiou's composition, incompletely setting the 5 those that are conventional in the industry of 'asbestos and cement sheets, with thejexception of the proportion of the impregnating material. 'I'hus, there'may be used about '25 to 50 parts by weight of asbestfi fibres, of a length commonly used in the nan actur'e of asbestos and cement sheets, shingles, or siding' units," 3 5 to 50 parts of Portland cement and 20 toil) parts of inert filler, say,'ratH er fine sawdust, for each 100 parts dry f employed; the proportion of impregnating jmaterial' is'substantially less than thatrequired to give complete saturation. I prefer touse, for instance, only about one-half to three-quarters of the proportionof impregnating material ordinarily employed in making ut unimpregnated sheet.

a fully'iinp'regnatedsheet, ."In atypical product also, the product resulting from and the method of incompletely impregnating a fibre-cement article with a il1 1 id. composition adapt'dTB'Flow- I ered in viscosityb'ywar'ming," and then warming to cause flowing of the impregnating material inwardly, away from the outer surface portions of the impregnated article.

The hggraulic cementitious materiahusedin my inven o one requiring a relat vely long setting time and exhibiting high strength after Among such fillers that may be used are sagdust, slate dust, or finely divided diatomaceous earth. V Impregnating materials that may be used, means of. the common .cardboard machine, com- -n'ionlycalled the wet machine in the asbestos either. alone Etfiiidd with'eachother, should constitute waterproofing, that is, should substantially prevent access of moisture to the cementitious material in the finished product, so that setting. The agrggnd cement is preferrediand has outstanding a n 'ages for the presentpurl ers may e used to lighten, make less madein aecordance withfthis invention, there is PI n .a 9 t4 t 8 Pa s y we ht t ggk t ial to 100 parts of bther'in res a result, a substantial propo' RT on of space originally presentin the pregnated sheet is left unfilled.

Various fother conventional admixtures; such as i' cuts or agents for a A l r tin the hardening 0? EH e impregnating material, maybe iiithe latter is impregnated.

c'orporatedC'For (example, vcommercial" er may be mixed into the selected drying oil ore The jyarious ingredients other, than the impregnating material are formed into awet mixture with water, the: water being in excess of the amount requir to hydrate the cementitious materialand, preferably, making the mixture plastic, so that. it will flow when compressed be tweenshaping members. This mixtur or composition is then shaped and strongly compressed, as, for instance, into sheet form, with the elimination of a large part of the excess water.

' .fThe shaping of the mixture may be effected by and cement sheet industry. 'In' the use of this there is no appreciable hardening of the impregnated article during storage at atmospheric temperature for two months or so.

' Among the impregnating materials that may oe used are waxes a drying oil, as, for example, linseed, perilla, citir -"fwmachine and method, the cement and fibres, either with or without the pigmentary' om mung gateriajrraremxed l'fit'fi i'n ggueoug 515s;

e, o ygjfif1: :vy ater and then iormed'into a wet p astic sheet ohtfie rotating,.receiving drum of the machine. When the thickness of layer on the drum has'been built up approximately to that desired, the sheet is removed from the drum, shaped into the form selected, usually flat, and strongly compressed between shaping members,

Q! ea a ste l pl t s- T e m r ssism i ardp-m-h. f

mitted to become about one-thirg tothre'e iourtgs .1 f fully, set, these terms eamng set e ex en I arch ong gg'g t g. h c m li ae l ari e answa ro sets?'neaifineacfetrsmiigtrtaa Portland cement. For instance, e se ifig'is allowed to proceed for approximately ten to twentyone days (as compared to twenty-eight days normally), after which time furthersetting is preve'nted.' 5 f Arresting of the cure "and prevention of fur ther'setting is produced by prompt drying of the thus partially set cementitious article, The grgr i g may be effected at atem ratur'e'above e 5 Mill; gf a ge u, maintained "iorafiay or. 1 so, eac sWeirfg'spaced from other. sheets or other large'sur'face during the drying operation. In a typical procedure, the sheets madefas' de- 1 .1 scribed that'arle. to be dried are: arranged with metal rods or asbestos strip separators between adjacent sheets. The assembly is then subjected to'a temperature of abou' 30.0%; for eighteen hours. This procedure pr uces ry'o'r-f substantially dry sheets, as the terms are used 35 herein. f f "The sheets so made are preferably treated to prevent resumption of the setting operation on ex posure to the atmosphere. Thus, there may be impregnated a waterproofing ,agentj oijith kind 4( described above. 1 i For this impregnation, the'spaced sheets, pref 1- erably arranged vertically and inthejasSembb with rod or strip separatorsdescribed above, are immersed in a bath of the impregnating material in liquid form. Using the dryingpils l preifer to immerse the sheets in the. oil at- 'anele'vateftemperature, say, atabout200 to 300 F, For best results, the impregnation is made in". complete. For instance; I keep the sheets immersed in the impregnating bath luntil the outer portions only of each sheet are "mipregnated;

On the other hand, the amountof impregnating material introduced should be adequate to prevent entrance: of moisture into the finished sheet. 5

I find these conditions to be met when there is left, directlyafter the immersion of the sheet in the impregnating'jjmateriah an unimpregnated core corresponding to about one-fourth to one half of the total thickness'of the sheet. "With the impregnating 'material of 'the consistency of linseed oil at 240 F., an immersion time of about three minutes is adequate i'or sheets of one-half inch thickness.-

' h The impregnated sheets are next subjected to treatment to harden the-impregnated material. Iffasphaltic or like materials have been used, they are hardened-by cooling thesheet to atmospheric temperature, after evaporation of any volatile extenders'or solvents thatiii'ay have beenused to promote fluidity for impregnation. When drying oils have been used, they are hardened by baking-the impregnated sheets'in contact with air. Thus, sheets impregnated with drying oils may be baked at about 300 w 475i-F'.,for.se'veral hours 7'5- to half a day, to cause oxidation and hardening of the oil.

Finally, the sheets are cooled to atmospheric temperature.

They may then be polished, as by sanding the surface that is to constitute the face of the sheet or panel during use. They may be sawed or trimmed to desired length and breadth.

Lacquers may be used to finish the sheets, as, for instance, conventional lacquers including, as the hinder or base, a polymerized resinous vinyl compound, pyroxylin, glycerine phthlate, and/or ,a resinous phenoialdehyde compound.

1.Special advantages have been found in the incomplete impregnation described above. Incompletely impregnated sheets, when later maintained at a temperature above the liquefying point of the impregnating material, as, for example, during the baking operation described or du'ring subsequent use, undergo appreciable flowingjof the impregnating material from the outer portions ofthe sheet towards the inner unimpregna'ted portion. There is thus avoided exudation of the impregnating material on, the face of the sheet. Furthermore, the proportion of impregnating material is inadequate to fill an of the void spaces .betweenthe particles of fibro ce'r'nent composition. v The result is avoidance' of any continuous smooth film of impregnating material on the fact of the sheet and, conversely, sufiicient porosity at the face to permit theproper footing or adherence of a lacquer applied as a finishing material over the sheet.

' As a result of the process described, there is produced a sheet that, although desirably strong for structural purposes, is much more readily sawed cut, or drilled than comparable asbestos and cement products in which the cement is fully set. Furthermore, there is less 'dangr of cracking such sheets during nailing with ismallnails' or working with usual tools. Although the incompletely cured'asbestos and cement sheet is relatively weak 'and brittle before impregnation, the impregnation and baking areaccompanied by a noticeable increase in the strength of the sheet. The sheet becomes tough, while remaining more or less flexible.

*"The details given are .for the purpose of iilustration, not restriction, and variations within enforcing fibres distributed therethroughout, the

Portland cement being incompletely hydrated and about one-third tothree-fourthsiully set.

, *2. 'A'n-articleof manufacture as described in claim 1, "including'a waterproofing agent impregnated into the said composition and preventingaccess of moisture to the partially set hydraulic cementitious material. I

3. An article of manufacture as described in clai1n l, including a drying oil impregnated into the "saidcomposition and preventing access of moisture to the partially se't hydraulic cementitious material, the drying oil being in hardened condition;

4. An article of manufacture comprising a dry, waterproofed, strongly compressed composition its. cowosmous,

comma on msm Cross Reference Examiner including partially hydrated Portland cement, 5. An article of manufacture as described in in largely but incompletely set and hardened claim 1, including a waterproofing agent imcondition, fibres distributed therethroughout, pregnated into the exterior portions only of the and an impregnated drying oil, the drying oil article and constituting approximately 4 to 8% being in hardened condition and being present 5 of the entire weight of the article.

in limited proportion leaving unfilled a substantial amount of the void space within the said JOHN C. MACILDOWE.

" composition. 

